SAT Writing section question
I'm not a native English speaker. I can talk fluently and believed that I had pretty good grammar until I took a few practice tests for the writing/grammar section. I keep getting like -15. I'm not familiar with a lot of grammar rules :/ Would it take me a very long to improve my score studying through prep books because I remember people saying how non-native speakers have a disadvantage in this section.
P.S.: I also went to a middle school and go to a high school with little emphasis on grammar rules and stuff.